JP3969265B2 - Magnetic tape device and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic tape device and a control method thereof, and more particularly, to a magnetic tape device and a control method thereof that prevent inadvertent overwriting of data due to a tape slip.
[0002]
[Prior art]
In a magnetic tape device, a phenomenon called slip in which the tape does not follow the rotation of the drive shaft may occur due to loose winding of the tape. If slip occurs when writing to the magnetic tape, data cannot be written from the correct location, and the written data is overwritten on the existing data, or conversely, the IBG (Interblock Gap) provided at the end of the existing data And a data head IBG to be additionally written, a gap is generated, and data cannot be read thereafter.
[0003]
In order to eliminate problems caused by tape slip, there is a write control method for magnetic tape devices that reads existing data blocks, detects that there is no data and then runs the tape for a certain distance and then writes the data. (For example, patent document 1). In addition, there is a magnetic tape control system that detects the presence or absence of slip by measuring the time until write data is read by the read head, and delays data writing when a slip occurs (for example, Patent Document 2).
[0004]
In addition, an error detection circuit connected to the block detection circuit and the tacho pulse counter is provided to detect the slip amount, and an error averaging circuit that averages the detected error and inputs it to the mileage control circuit is added to make it accurate. There is a magnetic tape device that realizes a repositioning operation (for example, Patent Document 3).
[0005]
[Patent Document 1]
JP 58-17554 A
[Patent Document 2]
JP 59-30256 (page 2, lower right paragraph)
[Patent Document 3]
JP-A-62-102451 (page 3, upper left paragraph)
[0006]
[Problems to be solved by the invention]
However, all of the above-mentioned conventional technologies read the magnetic tape to detect the end of the existing data, calculate the time and travel distance from there, and secure an appropriate length of IBG, and more appropriately By the way, it is necessary to perform processing such as sending additional data and starting data writing at the timing of writing to the magnetic tape. Accordingly, processing to be performed by the magnetic tape device is concentrated at the timing of writing, and an excessive load is applied to the MPU and bus of the device. If this process is actually realized, there is a problem that high performance of the circuit is required, which is not practical in terms of cost.
[0007]
In view of such a problem, the present invention detects an error due to slip and a necessary correction amount by locating to the last IBG, and starts writing at the corrected timing at the data end portion, thereby processing burden. An object of the present invention is to provide a magnetic tape device in which the above-mentioned is reduced.
[0008]
[Means for Solving the Problems]
In order to achieve this object, a magnetic tape device according to the present invention includes a servo motor that drives and drives a magnetic tape, a counter unit that counts pulse signals output from the servo motor at every predetermined rotation angle, and the magnetic tape device. IBG detection means for detecting IBG and outputting a first signal when the tape is running, a register for storing the count value of the counter means when the first signal is detected, and the counter means in the additional write operation of the magnetic tape Second signal output means for outputting a second signal when the value of the register becomes the value of the register, and comparison means for detecting the presence / absence and amount of tape slip by comparing the detection timings of the first and second signals. Prepared,
  The register includes at least an IBG (hereinafter referred to as a “final IBG”) that is to start additional recording on the magnetic tape and an immediately preceding IBG.(Hereafter referred to as “the last IBG one last”)And storing the count value at
  The comparison means includes
(1) When the second signal is detected earlier than the first signal in the last IBG portion immediately before the last, the timing to the magnetic tape is delayed by that amount from the second signal output time in the last IBG portion. I gave a postscript start command,
(2) In the IBG portion immediately before the last, the first signal is detected simultaneously with the second signal or the second signal is detected later than the first signal, and the error is within 1 mm as the distance on the magnetic tape. If there is, issue a command to start appending to the magnetic tape when the second signal is output in the final IBG portion.It is characterized by.
[0010]
As described above, in the magnetic tape apparatus of the present invention, an error is detected by positioning it at the last IBG in the additional write operation on the magnetic tape, and an additional write start command is issued at the timing for correcting the error in the final IBG portion. I have to. Therefore, the processing burdened by the device side in the final IBG portion where additional recording should be started is reduced, and it is possible to reduce the cost of the device by eliminating the need for high performance of the circuit.
[0011]
The comparing means includes
(3) The second signal is detected later than the first signal in the last IBG portion, and the error is the distance on the magnetic tape.When larger than 1mmIt is desirable to prompt the magnetic tape device to retry the write-once operation. In this case,
(4) Also by the retryGreater than 1mmWhen an error is detected, it is desirable to request the apparatus to perform a read operation from a portion before the last previous IBG to update the value of the register and then perform an additional write operation again.
[0012]
As will be explained later,Greater than 1mmIf additional writing is started when slipping occurs, a gap is generated in the IBG and reading becomes impossible. Therefore, retry of the additional writing operation is performed and error detection is performed again. Also, by this retryGreater than 1mmWhen an error is detected, in order to update the value of the register for grasping the tape position on the apparatus side, reading is performed from before the last previous IBG, and then the additional writing operation is started again.
[0013]
In the magnetic tape device of the present invention, each IBG of the magnetic tape is configured to have a width of about 2 mm, and the IBG detection means detects the first signal when IBG is detected 1 mm on the magnetic tape. Is output. This is because if the IBG of the magnetic tape is 2 mm wide, the point when 1 mm is detected is exactly the center of the IBG. Further, an IBG for 1 mm of tape is provided at the head of data to be additionally recorded in the additional recording operation. This is because the IBG of the portion where the additional recording is started is set to 2 mm to 3 mm.
[0014]
On the other hand, a method for controlling a magnetic tape device according to the present invention is a method for controlling a magnetic tape device in the case where new data is appended to the end of data written on the magnetic tape.
  Counter means for counting a pulse signal output at every predetermined rotation angle from a servo motor that drives the magnetic tape when detecting a first signal that is output when IBG is detected when the magnetic tape is running. The count value is stored in a register, and in the additional recording operation of the magnetic tape,Positioning the last IBG in the magnetic tape,Comparing the detection timing of the first signal with the detection timing of the second signal that is output when the value of the counter means becomes the value of the register, and detecting the presence or absence of a tape slip; and
  Position it as the final IBG,In the last IBG, if the tape position stored on the device side is the same as the tape position actually obtained by reading out the IBG or within 1 mm behind, the device side stores in the final IBG. At the timing of the tape positionAnd a step of starting the additional writing of data.
[0015]
In this method, when the tape position stored on the device side in the last previous IBG is earlier than the tape position actually obtained by reading the IBG, the device side stores in the final IBG. It is desirable to start adding data at a timing delayed from the tape position. Also, in the last IBG, if the tape position stored on the device side is the same as the tape position actually obtained by reading the IBG or within 1 mm behind, the device side stores in the final IBG. It is desirable to start adding data at the timing of the tape position. This is to prevent inadvertent overwriting of existing data and prevent data read errors.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a magnetic tape apparatus according to the present invention. As shown in FIG. 1, the magnetic tape device 1 includes a controller 10 that exchanges data with the host device 100, and a drive 20 that writes and reads data to and from the magnetic tape.
[0017]
The controller 10 has an MPU 11 that controls the operation of the entire controller 10, a write data generation circuit 12 that converts input data from the host device 100 into a format for writing to a tape, and a format that outputs read data from the drive 20 to the host device. A read data detection circuit 13 for converting to a GAP OUT signal, a GAP OUT signal generation circuit 14, and a GAP IN / OUT signal comparison circuit 15.
[0018]
The drive 20 includes a drive control MPU 21 for controlling the entire drive 20, a drive drive unit 22 for running and reading / writing a magnetic tape, a pulse signal counter 23, a counter storage register 24, and a GAP IN signal generation circuit. 25. The drive drive unit 22 includes a servo motor 26 that drives the magnetic tape to travel, and the servo motor 26 outputs a pulse and a signal indicating the rotation direction for each specific rotation angle. The drive drive unit 22 includes other components necessary for reading and writing data on the magnetic tape such as a read head and a write head, but the description thereof is omitted because it is not directly related to the present invention.
[0019]
When the MPU 11 of the controller 10 receives a data write command from the host device 100, the MPU 21 for drive control of the drive 20 commands to write the tape, and the write data generation circuit 12 sends the write data sent from the host device 100 to the magnetic tape. Is converted to a writable format and sent to the drive drive unit 22 via the write data bus 31. As will be described later, the write data generation circuit 12 starts transmission of write data with the GAP IN signal input from the GAP IN / OUT comparison circuit 15 as a trigger. In the drive drive unit 22, a servo motor 26 operates, and write data is written from the write head to the magnetic tape.
[0020]
On the other hand, when the MPU 11 of the controller 10 receives a data read command from the host device 100, a read command is issued to the drive 20, and data is read by the drive drive unit 22. The data read here is sent to the read data detection circuit 13 of the controller 10 via the read data bus 32, where it is converted into a data format that can be recognized by the host device 100 and sent to the host device 100.
[0021]
In the operation of the magnetic tape device 1, the servo motor 26 generates a pulse and a signal indicating the rotation direction at each specific rotation angle, and this signal is output to the pulse signal counter 23. The pulse signal counter 23 is a means for the drive 20 to grasp the current position of the tape. The pulse signal counter 23 counts up / down with reference to a signal indicating the rotation direction with the pulse signal output from the servomotor 26 as a trigger. This count value is reset when the tape is loaded.
[0022]
Data is read and written for each data block, and a predetermined length of IBG (interblock gap) is provided between adjacent data blocks written on the magnetic tape (see FIG. 2). When the magnetic tape is read, various marks such as IBG are also read by the drive driving unit 22 and sent to the read data detection circuit 13. According to the current standard, the maximum value of IBG is 3 mm (Typ 2 mm). Further, in the magnetic tape device, when data is written, the data is simultaneously read and the written data is confirmed (read after write function). Accordingly, the data block and the IBG are output to the read data detection circuit 13 at the time of reading / writing of the magnetic tape.
[0023]
The read data detection circuit 13 converts the read data into a data format that can be recognized by the host device 100, but also detects various marks in the process of analyzing the tape format. When the read data detection circuit 13 detects an IBG pattern among the detected marks, the read data detection circuit 13 outputs the detection signal to the GAP OUT signal generation circuit 14. The GAP OUT signal generation circuit 14 generates a GAP OUT signal when IBG is detected 1 mm at a distance on the tape from the input length of the IBG pattern detection signal. The GAP OUT signal is sent to the drive 20 and the GAP IN / OUT signal comparison circuit 15. However, as will be described in detail later, the GAP OUT signal is output only to the comparison circuit 15 and is not sent to the drive 20 at the time of locating accompanying writing.
[0024]
FIG. 2 shows the relationship between the tape data format and the GAP OUT signal. In the magnetic tape, IBGs and data blocks are alternately provided. In this embodiment, the length of each IBG is set to 2 mm. In this tape read processing, when the IBG detection length output from the read data detection circuit 13 to the GAP OUT signal generation circuit 14 becomes 1 mm, that is, when the tape approaches the center of the IBG on the tape, the GAP OUT signal is output. It is transmitted to the counter storage register 24.
[0025]
The counter storage register 24 stores the counter value of the pulse signal counter 23 every time the GAP OUT signal output from the GAP OUT signal generation circuit 14 is received. As shown in FIG. 1, the counter storage register 24 includes two registers 24a and 24b, and stores a pulse count value while overwriting old information alternately. Accordingly, the values indicated by the two registers 24a and 24b are a pulse count value when the last GAP OUT signal is received and a pulse count value when the last GAP OUT signal is received. The count value of the register 24 is referred to by the drive control MPU 21 and the GAP IN signal generation circuit 25.
[0026]
The GAP IN signal generation circuit 25 operates only when data is written, and monitors the count value of the pulse signal counter 23 with reference to the count value recorded in the counter storage register 24. Then, when the count value indicated by the pulse signal counter 23 matches the value recorded in the register 24, a GAP IN signal is generated and output to the GAP IN / OUT signal comparison circuit 15. That is, the GAP IN signal generation circuit 25 transmits a GAP IN signal to the comparison circuit 15 when it reaches the IBG position on the tape stored on the drive side.
[0027]
The controller-side GAP IN / OUT signal comparison circuit 15 receives the GAP IN signal and the GAP OUT signal, detects an error in the input timing of the two signals, and determines the presence / absence and degree of tape slip. As will be described in detail later, the error detection of the input signal is performed on the last IBG portion. Then, the GAP IN signal is output to the write data generation circuit 12 at the timing when the error is corrected in the final IBG. The write data generation circuit 12 starts outputting write data to the drive driver 22 at the timing when the GAP IN signal is input from the comparison circuit 15. In the case of appending data (append write), as shown in FIG. 3, the format of the write data is 1 mm for the first IBG, and 2 mm for the IBG provided after the data block.
[0028]
In the magnetic tape device 1, the operation when data written on the magnetic tape is read to the end and a new data block is appended (append write) after the last data block will be described below.
[0029]
In FIG. 1, when receiving a data read command from the host device 100, the MPU 11 of the controller 10 receives this command and commands the drive 20 to read the tape. This read command is sent to the drive 20 via the write data bus 31 to start reading the tape. In the read process, the read data of the drive drive unit 22 is sent to the read data detection circuit 13 of the controller 10 via the read data bus 32. This read data includes a data block and various marks (see FIG. 2). Since the data block cannot be recognized by the host device as it is, the data format is converted by the read data detection circuit 13 and sent to the host device 100. Further, when the read data detection circuit 13 detects an IBG pattern written to identify data blocks among the marks, it outputs an IBG pattern detection signal to the GAP OUT signal generation circuit.
[0030]
The GAP OUT signal generation circuit 14 monitors the input IBG pattern signal and outputs the GAP OUT signal to the drive 20 when IBG is detected 1 mm at a distance on the tape. This GAP OUT signal enters the counter storage register 24 of the drive 20 via the GAP IN / OUT signal line 33. The counter storage register 24 records the counter value of the pulse signal counter 23 that counts the pulse signal from the servomotor 26 in the register at the timing when the GAP OUT signal is received. As described above, the count value is alternately overwritten in the two registers 24a and 24b. In this way, the position on the tape where the GAP OUT signal is detected in the drive 20 is stored as the count value, and this position becomes the reference point for positioning the tape. This register recording operation is continuously performed while the tape is read by the drive 20.
[0031]
After reading the last data written on the tape, the host device 100 commands the appending of data (append write). With this command, the magnetic tape device 1 performs the write operation after the head is positioned (located) at the additional write start position. This series of operations will be described with reference to FIG.
[0032]
In the locate operation, the tape is rewound to the middle of the last data block. That is, the drive control MPU 21 reads the value of the register storing the last IBG count value in the counter storage register 24, and the count value of the pulse signal counter 23 is slightly smaller than the read value. The servo motor 26 is controlled. As a result, the tape is rewound to the point A shown in FIG. 4, and the read process is started again in the forward direction (the direction of the arrow in FIG. 3). The reason why the last IBG is rewound slightly before is to secure a distance necessary to make the tape travel in the forward direction a constant speed state. The count value read here (the count value at the time of the last previous IBG detection) is simultaneously sent to and stored in the GAP IN signal generation circuit 25.
[0033]
The GAP IN signal generation circuit 25 generates a GAP IN signal and compares it via the signal line 33 when the pulse signal counter 23 of the servo motor 26 indicates the count value read from the register 24 in the read process at the time of locate. Send to circuit 15. As a result, the GAP IN signal is input to the comparison circuit 15 at the last IBG position stored in the apparatus 1 as the pulse count value of the servo motor 26.
[0034]
The data read by the drive drive unit 22 at the time of the locate is sent to the controller 10. The sent data is analyzed by the read detection circuit 13, and a data block and a mark are detected. When the detection circuit 13 detects the IBG pattern, an IBG pattern detection signal is sent to the GAP OUT signal generation circuit 14, and a GAP OUT signal is generated when the IBG pattern is detected by 1 mm. As described above, the GAP OUT signal is not sent to the drive 20 at the time of locating, but is output only to the GAP IN / OUT comparison circuit 15. Similarly, at the time of locating, the read detection circuit 13 discards the data block without sending it to the higher-level device 100 according to a command from the MPU 11. As a result, the GAP OUT signal is input to the comparison circuit 15 at the IBG detection timing on the actually running tape.
[0035]
The GAP IN / OUT comparison circuit 15 compares the timing of the input GAP IN signal and the GAP OUT signal. As a result, the presence or absence of tape slip and its error are grasped at the last IBG point. That is, as shown in FIG. 4, when the GAP IN signal and the GAP OUT signal are simultaneously input to the comparison circuit 15, no tape slip occurs. If there is a deviation in the timing of the input signal, a slip has occurred, so the tape slip condition is confirmed and stored from the deviation direction and its amount.
[0036]
When the MPU 11 of the controller 10 confirms the comparison result in the GAP IN / OUT comparison circuit 15, it transmits a write command to the drive 20 and the write data generation circuit 12. Upon receiving the write command, the drive control MPU 21 reads the value of the register storing the pulse count value at the time of the last IBG detection in the counter storage register 24, and the servo motor so that the pulse signal counter 23 becomes this value. 26 is controlled. The read count value is simultaneously sent to and stored in the GAP IN signal generation circuit 25.
[0037]
When the pulse signal counter 23 of the servo motor 26 indicates the count value read from the register 24, the GAP IN signal generation circuit 25 sends the GAP IN signal to the comparison circuit 15 via the signal line 33. The comparison circuit 15 that has received this GAP IN signal branches the processing as follows according to the timing information and the deviation value recorded earlier.
[0038]
(1) When the GAP OUT signal and the GAP IN signal are simultaneously input in the last IBG, since no data slip has occurred, the comparison circuit 15 outputs the input GAP IN signal as it is to the write data generation circuit 12 ( (See FIG. 4). The write data generation circuit 12 starts transmission of write data to the drive driver 22 with the input of the GAP IN signal as a trigger, and data write is started in the drive driver 22. Here, as described above, the GAP IN signal is input to the comparison circuit 15 when IBG is detected at 1 mm, and the data format at the time of append write is set to 1 mm at the additional write start portion as shown in FIG. Therefore, the IBG that is the seam of the data is 2 mm, which is the same as the other parts.
[0039]
(2) When the GAP IN signal is detected earlier than the GAP OUT signal, the tape is shifted in the forward direction. This state is shown in FIG. In this case, the comparison circuit 15 delays the GAP IN signal by the amount of deviation and outputs it to the write data generation circuit 12. Thereby, the additional recording start position is corrected by the amount of deviation, and additional recording can be started without overwriting the already written data end portion.
[0040]
(3) When the GAP IN signal is detected later than the GAP OUT signal, the tape is displaced in the reverse direction. At this time, the comparison circuit 15 refers to the amount of deviation, and if the deviation is within 1 mm, outputs the GAP IN signal to the write data generation circuit 12 as it is. This state is shown in FIG. As a result, the GAP IN signal is sent to the write data generation circuit 12 at a timing slightly delayed from the examples shown in FIG. 4 and FIG. 5, and the IBG at the additional write start portion has a maximum length of 3 mm as shown in FIG. According to the standard (ANSI), since the maximum length of IBG is 3 mm (Typ 2 mm), there is no problem that reading is impossible.
[0041]
(4) GAP IN signal is detected later than GAP OUT signal.Greater than 1mmIn this case, the GAP IN / OUT comparison circuit 15 does not output the GAP IN signal and requests the MPU 11 to re-execute the locate and write instructions. If the GAP IN signal is output to the write data generation circuit 12 as it is, a gap is generated between the last written IBG and the additional recording start IBG, resulting in an unreadable tape that violates the tape format. Because.
[0042]
It is sufficient if the patterns (1) to (3) above can be achieved by re-execution of locate and write.Greater than 1mmIf slip has occurred, a similar error is detected. Therefore, if the same result is obtained even after several retries, reread from the last data block to the last data is performed, and append write is executed again. By rereading, the value of the counter recording register 24 is updated, and append writing can be successful. Note that the read data during the reread process is discarded without being sent to the host apparatus 100.
[0043]
Although the embodiment of the present invention has been described in detail, a part of the circuit may be abolished in the above embodiment and replaced with MPU and firmware. For example, the gapin / out comparison circuit 15 may be eliminated, and slip detection and compensation may be performed by firmware.
[0044]
【The invention's effect】
As described above, in the magnetic tape device and the control method thereof according to the present invention, the tape slip is detected at the last IBG portion, and the GAP IN signal output from the comparison circuit 15 according to the detection result. By adjusting the output timing, the deviation is corrected in the final IBG portion. Therefore, it is possible to disperse the processing burden of the apparatus as compared with the case where slip compensation is performed at the end portion of the traveling magnetic tape, and it is possible to reduce the cost and size of the apparatus.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a magnetic tape device according to the present invention.
FIG. 2 is a diagram illustrating a relationship between a data format at the time of reading and a GAP OUT signal;
FIG. 3 is a diagram showing a data format during append write.
FIG. 4 is a diagram illustrating an example of processing during append writing.
FIG. 5 is a diagram for explaining an example of processing during append writing.
FIG. 6 is a diagram for explaining an example of processing during append writing.
[Explanation of symbols]
1 Magnetic tape unit
10 Controller
11 MPU
12 Write data generation circuit
13 Read data detection circuit
14 GAP OUT signal generation circuit
15 GAP IN / OUT signal comparison circuit
20 drives
21 MPU for drive control
22 Drive drive unit
23 Pulse signal counter
24 Counter storage register
25 GAP IN signal generation circuit
26 Servo motor
31 Write data bus
32 Read data bus
33 GAP IN / OUT signal line

Claims (7)

Servo motor for driving the magnetic tape, counter means for counting pulse signals output from the servo motor at every predetermined rotation angle, and detecting the IBG when the magnetic tape is running and outputting the first signal An IBG detecting means; a register for storing the count value of the counter means when the first signal is detected; and a second signal that outputs a second signal when the value of the counter means becomes a register value in the additional recording operation of the magnetic tape. Two-signal output means, and comparison means for comparing the detection timing of the first and second signals,
The register has at least an IBG (hereinafter referred to as “final IBG”) and an immediately preceding IBG (hereinafter referred to as “final IBG”) that are to start additional recording on the magnetic tape . And storing the count value at
The comparison means includes
(1) When the second signal is detected earlier than the first signal in the last IBG portion immediately before the last, the timing to the magnetic tape is delayed by that amount from the second signal output time in the last IBG portion. I gave a postscript start command,
(2) In the IBG portion immediately before the last, the first signal is detected simultaneously with the second signal or the second signal is detected later than the first signal, and the error is within 1 mm as the distance on the magnetic tape. In some cases, a magnetic tape device is characterized in that a command to start appending to a magnetic tape is issued when a second signal is output in the final IBG portion . 2. The magnetic tape device according to claim 1, wherein the comparing means is
(3) When the second signal is detected later than the first signal in the last IBG portion and the error is larger than 1 mm on the magnetic tape, the write operation is retried to the magnetic tape device. A magnetic tape device characterized by the following. 3. The magnetic tape device according to claim 2, wherein the comparing means is
(4) When an error larger than 1 mm is detected even after the retry, the read operation is performed from the portion before the last IBG, the value of the register is updated, and the additional operation is performed again. A magnetic tape device characterized by requiring the device.   4. The magnetic tape device according to claim 1, wherein each IBG of the magnetic tape is configured to have a width of about 2 mm, and the IBG detection means detects IBG on the magnetic tape by 1 mm. And outputting the first signal when the magnetic tape device operates.   5. The magnetic tape device according to claim 1, wherein an IBG for 1 mm of tape is provided at the head of data to be additionally recorded in the additional recording operation. In the control method of the magnetic tape device when appending new data to the end of the data written on the magnetic tape,
Counter means for counting a pulse signal output at every predetermined rotation angle from a servo motor that drives the magnetic tape when detecting a first signal that is output when IBG is detected when the magnetic tape is running. The count value is stored in a register, and in the write-once operation of the magnetic tape, positioned at the last IBG in the magnetic tape, the first signal and the value of the counter means are set to the register value. Comparing the detection timing of the output second signal and detecting the presence / absence of a tape slip and its error;
If the tape position stored on the device side is the same as the tape position obtained by actually reading the IBG or within 1 mm behind the last IBG, the final IBG is positioned . A method of controlling a magnetic tape device, comprising: a step of starting to add data at a timing of a tape position stored on the device side in IBG .   7. The method of controlling a magnetic tape device according to claim 6, wherein the tape position stored on the device side is before the tape position actually obtained by reading the IBG in the last IBG. A method of controlling a magnetic tape device, wherein data addition is started at a timing delayed from the tape position stored on the device side in the final IBG.

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